Presently, the future of motorized society depending on petroleum has been feared, and hence there is expected the spread of a car on which a fuel cell using hydrogen as a fuel is mounted. The fuel cell has a stack structure where cells are stacked in series, and generates a power by use of an electrochemical reaction between a fuel gas containing hydrogen supplied to an anode and an oxidizing gas containing oxygen supplied to a cathode.
In the fuel cell, various restrictions exist during startup as compared with another power source. The power generation efficiency of such a fuel cell deteriorates owing to the drop of temperature and the poisoning of an electrode catalyst, with the result that a desired voltage/current cannot be supplied, and hence an apparatus cannot be started sometimes.
In view of such a situation, at the start of the fuel cell, an operation of recovering the current/voltage characteristics (IV characteristics) of the fuel cell (hereinafter referred to as a refresh operation) is performed by causing the short state of at least one of the fuel gas supplied to the anode and the oxidizing gas supplied to the cathode, so that the overvoltage of a part of an electrode is increased, thereby further generating heat, raising the temperature of the fuel cell, and reducing the electrode catalyst (see, e.g., Patent Document 1).
[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-504807: Translation version